Syncro operation

[ld50]

Great stuff Mike – there was a page in the links section which used to cover a lot fo this stuff but the page itself is long gone now so this is great info to have all in the same place.

[Audi Doody]

I have been asked to expand on a couple of things that I hope will give a more complete picture of VAG Syncro/Quattro transmissions.

Audi Quattro Transmission
As far as I can find out this transmission system came in 2 variants. The best was a transmission system using Torsen Limited Slip Differentials on each axle and also as a centre differential.
The 2nd variant used conventional axle differentials with a Torsen centre differential
The TORque SENsing differential is based on gear wheels to limit the amount of slip and although being very strong and quick acting, they do have a minor disadvantage, they can only pass 80% of the power applied to them.
A VC unit when fully locked will pass 100% of the power applied.

Syncro Viscous Coupling repairs.
Every now and then a question is asked on the Syncro site about repairing or “topping up” a VC unit.
At this time there is no means of being able to repair a VC unit.
The fluid is not available, nor is the spec of the fluid known, and lastly the amount of fluid in the VC unit is an exact amount. The quantity and type of fluid in the VC unit determines its “locking” characteristics.
If they show any sign of leaking, get a replacement.

A quick check on ETKA shows that a VC unit is not a “exchange” item so even VAG do not repair them.

[dubs4life7]

very nicely put together man. it was a great read and very informative thanks

[cdn_syncro]

quote:

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Originally posted by Audi Doody
Syncro Viscous Coupling repairs.
Every now and then a question is asked on the Syncro site about repairing or “topping up” a VC unit.
At this time there is no means of being able to repair a VC unit.
The fluid is not available, nor is the spec of the fluid known, and lastly the amount of fluid in the VC unit is an exact amount. The quantity and type of fluid in the VC unit determines its “locking” characteristics.
If they show any sign of leaking, get a replacement.

A quick check on ETKA shows that a VC unit is not a “exchange” item so even VAG do not repair them.

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there must be some way of finding out from vag or the manufacturer of specs of the vc unit. somebody, somewhere knows who made the fluid and how much of it goes in the vc.

[alangjones44]

Brilliant.[] Thanks very much. Great explanation

[Chris S]

Considering that VW last fitted a VC unit in 1997 before they switched to Haldex for the 1998 Golf models, I very much doubt that there is any one at VW who knows anything about its internals at all.

And if you also take into consideration that it was first fitted to a production VW in 1985, which must mean that the development work will have been completed in the early 80s, it then becomes even more unlikely that there is anyone remaining at VW who had any part in the design or developement work.

[Ademaxx]

quote:

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Originally posted by cdn_syncro

quote:

---

Originally posted by Audi Doody
Syncro Viscous Coupling repairs.
Every now and then a question is asked on the Syncro site about repairing or “topping up” a VC unit.
At this time there is no means of being able to repair a VC unit.
The fluid is not available, nor is the spec of the fluid known, and lastly the amount of fluid in the VC unit is an exact amount. The quantity and type of fluid in the VC unit determines its “locking” characteristics.
If they show any sign of leaking, get a replacement.

A quick check on ETKA shows that a VC unit is not a “exchange” item so even VAG do not repair them.

---

there must be some way of finding out from vag or the manufacturer of specs of the vc unit. somebody, somewhere knows who made the fluid and how much of it goes in the vc.

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Just thought I’d let everyone know you CAN buy the viscous fluid to go into the viscous coupling. I have managed to open my VC and refill with 100,000 wt silicone. This is available to buy in 500g tubs (more than enough to fill one coupling) I sourced it from a Company in Germany. They were very helpful and replied to my emails very quickly, Here is the link to the page for the fluid, it cleary states for use in vw syncro systems.

http://www.silikon-profis.de/index.php?f=sysnr&c=0003_10011&t=artikel&sid=a245143f315eb6fd649976df0da2c837

Hope this helps someone else out there!! []

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